This invention relates in general to an information storage device which includes a hard disk and, more particularly, to such an information storage device in which the hard disk is disposed in a removable cartridge.
Over the past twenty years, computer technology has evolved very rapidly. One aspect of this evolution has been a progressively growing demand for increased storage capacity in memory devices, especially where the information storage medium is disposed in some form of removable cartridge. In this regard, just a little over a decade ago, the typical personal computer had a floppy disk drive which accepted floppy disk cartridges that contained 5.25xe2x80x3 disks having a storage capacity up to about 720 KB per cartridge. Not long thereafter, these devices gave way to a new generation of floppy disk drives which accepted smaller floppy disk cartridges that contained 3.5xe2x80x3 disks having higher storage capacities, up to about 1.44 MB per cartridge.
Subsequently, as the evolution continued, a further significant increase in storage capacity was realized in the industry by the introduction of a storage system having removable cartridges containing floppy-type disks with storage capacities on the order of 100 MB to 250 MB. Systems of this are commercially available under the tradename ZIP from Iomega Corporation of Roy, Utah, which is the Assignee of the present application. Thereafter, another significant increase in storage capacity was realized by the introduction of a system having removable cartridges with storage capacities on the order of 1 GB to 2 GB. Systems of this type are also available from Iomega Corporation, under the tradename JAZ. The cartridges used in this system had a hard disk in an unsealed housing, with the read/write head in the drive. These two products have each enjoyed immense commercial success. Nevertheless, the demand for still greater storage capacities in removable cartridges continues to progressively increase, such there is a current need for cartridges capable of storing 5 GB to 20 GB, or even more.
The types of removable cartridges discussed above each contain a rotatably supported storage medium within an unsealed housing. The read/write heads, with associated circuitry and support structure, are in the drive rather than in the cartridge. Significantly higher storage capacities exist in hard disk technology of the type used in non-removable hard disk drives, where the disk and head are both within a sealed housing. However, there are problems involved in attempting to carry use of this technology over to removable cartridges. This is due in part to the fact that a high-capacity hard disk is highly sensitive to environmental factors such as dust and static electricity. Consequently, in order to achieve high storage densities, the sealed housing is needed for the hard disk itself, as well as for some associated components, such as the read/write heads, which must be within the sealed housing and thus within the cartridge. Although some prior attempts have been made to use hard disk technology within a sealed housing in a removable cartridge, these attempts never resulted in a product which has had any significant level of commercial success. Instead, the types of cartridges discussed above continue to dominate the market.
Where a sealed housing has been used, the most typical prior approach was to incorporate the entire structure of a hard disk drive unit into the cartridge, such that the cartridge was not significantly different from a self-contained, standalone hard disk drive unit. In a sense, this was not a true cartridge at all, but simply a complete and self-contained hard disk drive which could be removed more easily than most from the system in which it was installed. One example of such a device is a system which was commercially available as the model P3250AR removable hard disk drive from Kalok Corporation of Sunnyvale, Calif. Another example of such a system is disclosed in Blackborow et al. U.S. Pat. No. 5,041,924. Since each cartridge in this type of system is effectively a standalone, self-contained disk drive, each cartridge is relatively heavy and expensive.
A different prior approach was to split the components of a self-contained hard disk drive into two groups, and to include one group within a sealed housing in each removable cartridge, and the other group in a drive which can removably receive one of the cartridges. Examples of this approach appear in Stollorz U.S. Pat. No. 4,359,762, Iftikar et al. U.S. Pat. No. 4,965,691, Chan U.S. Pat. No. 5,214,550, Kamo et al. U.S. Pat. No. 5,235,481, Witt et al. U.S. Pat. No. 5,317,464, and Lockhart et al. U.S. Pat. No. 5,412,522. While pre-existing products using this approach were adequate for their intended purposes, they were not satisfactory in all respects, and none of them experienced any significant commercial success.
In this regard, one consideration is that, in a removable cartridge with a hard disk in a sealed housing, there will be components in the cartridge which are susceptible to damage from electrostatic discharge. For example, the cartridge will include a read/write head, and may also include electronic circuitry, such as a preamplifier for the read/write head. A connector will typically be provided on the exterior of the housing, in order to facilitate electrical connections between external circuitry and the components within the housing, while maintaining the integrity of the sealed housing.
Electrostatic energy may be inadvertently applied to a terminal of the connector at a time when the cartridge is removed from the drive, for example because a person holding the cartridge inadvertently touches the terminal after walking across a carpet which generates a static electric charge on the person""s body. Application of such an electrostatic charge to the terminal, and thus to electrical components within the cartridge which are coupled to the terminal, can result in permanent damage to those components. Consequently, in order to ensure the integrity and reliability of each cartridge, it is desirable that some provision be made to protect internal components from potential damage due to electrostatic discharge.
From the foregoing, it may be appreciated that a need has arisen for a method and apparatus for protecting components in a removable cartridge from potential damage due to electrostatic discharge. According to the present invention, a method and apparatus are provided to address this need in the context of an information storage cartridge which includes a port, an information storage medium, and a head which is electrically coupled to the port and operable to effect at least one of reading information from and writing information to the storage medium. The method and apparatus of the invention involve: supporting the head and the storage medium for relative movement in a manner causing the head to move relative to the surface while remaining adjacent thereto; and using an electrostatic protection portion to protect the head from electrostatic energy which originates externally of the cartridge.